Utah Plasma Jasper - Unknown Rock!

Utah Plasma is truly a mystery rock!

This article is about what I know about Utah Plasma … and what I don’t know. There are more things that I don’t know.

One of the things I don’t know is where the name comes from. Dictionaries list the “mineral” Plasma as ”a dark green, translucent variety of quartz”. Along with ”the colorless fluid part of blood, lymph, or milk” and “an ionized gas consisting of positive ions and free electrons“. If you can make sense out of that, you’re a better etymologist than I am.

Utah Plasma fails the dictionary definition on two counts. First, it’s not translucent. It’s a rhyolitic jasper and they’re never translucent. Second, it’s not always green. In fact, the most unique characteristic of Utah Plasma is the color: Green and red/orange. My dad and his friends should have called it "Hiberianite" after the Latin name for Ireland because it features the colors of Ireland – green and orange. But neither my dad or any of his friends knew any Latin.

In the beginning ... Where Utah Plasma Jasper came from

My career was computer software, so I really don't have any standing to talk about the geology of Utah Plasma Jasper. On the other hand, I have asked professional geologists about it and they don't seem to have any better ideas than I do. Geologists do have an impressive technical vocabulary to obscure the fact that they're guessing, just like we are. Professional geologists need to make a living too so they're experts in things where you can make a buck – like telling mining and oil companies where to rip up Mother Earth. Rocks that rockhounds like to collect isn't a core competency for most geologists. Few of them are paid to research pure science or hunt rocks for fun. For example, we knew that a massive meteor wiped out the dinosaurs, but we didn’t know where it landed. Chicxulub, the crater, was only found years later. Oil companies thought there might be oil there and did some core drilling to find out. When a geologist who was doing pure science was finally allowed to look at the drill cores, he ran down the street naked yelling, “Eureka! I have found it!” (Or, was that Archimedes?)

“Money” drives a fancy red sports car. “Scientific investigation” takes the bus.

A lot of rocks, and in particular, rhyolitic jaspers (there are lots of different varieties), are the silicified remains of volcanic explosions. In general, the recipe goes like this. Take one volcano and explode it. Make sure that the explosion leaves deep ash deposits. Bury the ash in sediment in a place where it won't be disturbed for 50 to 100 million years or so. Saturate the ash – which is now called “tuff” – with silica bearing groundwater, usually heated by more igneous activity, until the tuff is thoroughly silicified (turned into jasper or agate). Geologists will tut-tut you and tell you that it’s really rhyolite. Pat them on the head and say, “There, there. Call it whatever you want. We know what it is.”

The final step is to expose it to rockhounds and watch them squirrel it away like it was walnuts.

There are a lot of variations to this recipe. Salina Canyon Wonderstone, for example, is a lens that squeezed between other formations. It's only a couple of inches thick at most. The tuff hardened, broke into pieces, and was silicified after that. You can tell because each of the individual pieces still fit together in the ground like a stone jigsaw puzzle. But each piece is colored from the outside in with concentric spheres by millions of years of silicification.

Utah Plasma Jasper appears to be silica rich lava that was ejected through the air and landed while still semi-liquid. This accounts for the "puddle" shape and size. I think it looks a lot like a green stone "cow pie". Plasma and Salina Canyon Wonderstone are both colored with concentric spheres from the outside in to the center because they were converted from volcanic tuff to jasper the same way.

Utah Plasma will take a great polish. See the mirror reflection in the chunk below. It has few cracks and the green usually changes to orange in a smooth, gradual transition

What it is ... Utah Plasma as a gemstone

I have discovered that a rock called “plasma” is found in a few other places too. There is a local rock that is a milky white with little spots found in Maine called “plasma”. One rock seller speculates that it was carried there by glaciers from some formation much further north. There’s even a building material made from landfill waste called “Plasma Rock”. But none of it looks remotely like Utah Plasma Jasper. I have no idea how Utah plasma got that name but that’s what my dad and his friends called it. I’m still looking for information. If you know why these rocks are called “plasma” please tell me.

Where it is ... Finding it

In brief, you don't find it. Not anymore. Plasma, Salina Canyon Wonderstone, and Utah Grape Agate were all highly localized geological events. I believe that Utah Plasma weathered out of a formation that has been completely eroded away now. The Plasma was left sitting right there on top of the Mancos Shale – easy to find and easy to pick up. That is exactly what happened. There's none there now. I have yet to see any listed for sale in the years KinesavaROCKS has been in operation. If anybody else has any at all, I’d like to know about it.

It used to exist in the incredibly productive rockhounding territory near the San Rafael Swell. All I know for certain (I was just a little kid at the time. Now I’m a senior citizen.) is that my dad would turn off highway 6 at Woodside, where the Price River cuts through the Book Cliffs, and head south. At one point along the way, there was an area where Utah Plasma was scattered all over the ground.

Can You Get a Chunk?

In brief, yes. But not as much as you might want.

The KinesavaROCKS “Mission Statement” is, “I’m not really in business. I’m just having fun with my dad’s rocks.” I like sending rocks to people who will appreciate them and that includes Plasma.

But one thing I learned when I first started selling them: Plasma is incredibly popular. Not long after I posted the first version of this article years ago, I realized that at the rate my supply was flying out the door, I soon wouldn’t have any left. So, I quit listing it for sale while I decided what to do.

I was faced with a dilemma. When other rock sellers discover that they have a hit like this, they just raise their price. Yellowcat Wood, for example, is now only sold at auction for prices in five figures. That puts it completely out of range of regular rockhounds and that’s not how I define, “having fun”. I actually tried raising the price more than was comfortable to me. It didn’t seem to make a difference. People ordered it anyway.

Today, I sell a piece every now and then. Not being in business does give one a certain freedom to do whatever feels good at the time.